“The transition of VMFA-121 from MCAS Yuma to MCAS Iwakuni marks a significant milestone in the F-35B program as the Marine Corps continues to lead the way in the advancement of stealth fighter attack aircraft,” the statement said.

The jets had not arrived at Iwakuni as of Wednesday morning Japan time, said the base’s public affairs office, which did not provide information on when they would touch down.

Marines fly a “short take-off vertical landing” version of the plane, which is designed to replace F/A-18 Hornet, AV-8B Harrier and EA-6B Prowler jets.

In November 2012, VMFA-121, which had flown F/A-18 Hornets, became the Marines’ first operational F-35 squadron. Since then, it has taken part in numerous drills in the U.S. and was declared combat-ready in July 2015, the statement said.